Bonding, Structure, and the Properties of Matter

• Explain the difference in charges between ionic, covalent and metallic bonding?

  For ionic bonding the particles are oppositely charged ions.

  For covalent bonding the particles are atoms which share pairs of electrons.

  For metallic bonding the particles are atoms which share delocalised electrons.
• When does ionic, covalent and metallic bonding occur?

  Ionic bonding occurs in compounds formed from metals combined with non-metals.

  Covalent bonding occurs in most non-metallic elements and in compounds of non-metals.

  Metallic bonding occurs in metallic elements and alloys
• What happens when a metal atom reacts with a non-metal atom?

  When a metal atom reacts with a non-metal atom electrons in the outer shell of the metal atom are transferred.

  Metal atoms lose electrons to become positively charged ions. Non-metal atoms gain electrons to become negatively charged ions
• What is a ionic compound?

  An ionic compound is a giant structure of ions.

  Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions.

  These forces act in all directions in the lattice and this is called ionic bonding.
• Explain one advantage and disadvantage of using a 'Dot and Cross Diagram'.

  Dot and cross diagrams have an advantage because we use dots to represent the electrons from one atom and we use crosses to represent the electrons from another atom. It is very clear where the electrons are coming from.

  Dot and cross diagrams don't tell us the shape of the molecule.
• Explain some disadvantages of using a 'Two Dimensional Stick Diagram'.

  Because a covalent bond is shown as a stick we cannot tell which electron the in the covalent bond came from which atom.

  Stick diagrams also give us no idea of outer electrons that are not in bonds.

  Stick diagrams do not give us accurate information on the shape of the molecule.
• Explain a advantage of using a '3 dimensional stick diagram'.

  3 dimensional stick diagrams shows us the shape of the molecule
• Explain advantages and disadvantages of ball and stick diagrams.

  Ball and stick diagrams allow us to clearly see the ions in 3 dimensions however, the ions are shown as widely spaced when in reality they ions are packed together.
• Why do ionic compounds have a high melting point?

  -When solid, ionic compounds have a high melting point.

  -Ionic compounds exists as a Giant Ionic Lattice when solid.

  -Forces of electrostatic attraction between ionic bonds are very strong.

  -Within Giant Ionic Lattice there are many ions and ionic bonds.

  -It therefore requires a lot of energy to break apart the Giant Ionic Lattice, therefore melting point of ionic compound is high.
• Why can't ionic compounds conduct electricity when solid?

  -When solid, ionic compounds exists as a Giant Ionic Lattice.

  -Because of this, ions are not free to move and acts a charge carriers.

  -This means ionic compounds cannot conduct electricity when solid.
• Why can ionic compounds conduct electricity when melted or dissolved in water?

  -When melted or dissolved in water, ionic compounds conduct electricity because the ions are free to move and so charge can flow.
• Why can substances that consists of small molecules have relatively low melting/ boiling point?

  -These substances have only weak forces between the molecules (intermolecular forces).

  -It is these intermolecular forces that are overcome, not the covalent bonds, when the substance melts or boils.
• Why can substances that consists of small molecules not conduct electricity?

  Small molecules have no delocalised electrons to act as charge carriers.
• Why do metallic compounds have high melting points?

  -When solid, metals exists as a Giant Metallic Lattice

  -In the lattice there are many metallic bonds which are strong.

  -Therefore a lot of energy is needed to break these bonds.
• Why are metallic compounds good electrical conductors?

  Metals have a sea of delocalised electrons which can act as charge carriers.
• Why are metallic compounds soft and malleable?

  -Metals exists as layers of positive metal ions

  -These layer can slide over each other easily.
• Explain some properties of diamond.

  -very high melting point

  -cannot conduct electricity

  -hard

  -each carbon forms 4 covalent bonds
• Explain some properties of graphite.

  -very high melting point

  -can conduct electricity

  -soft and slippery

  -each carbon forms three covalent bonds
• Explain why diamonds have high melting points.

  -When solid, covalent bonds exist as a Giant Covalent Lattice

  -There are strong covalent bonds within the lattice and lots of bonds.

  -A lot of energy therefore is required to break these bonds.
• Explain why graphite has a high melting point.

  -When solid, covalent bonds exist as a Giant Covalent Lattice.

  -There are strong covalent bonds within the lattice and lots of bonds.

  -A lot of energy therefore is required to break these bonds.
• Explain why diamond cannot conduct electricity.

  -When solid, covalent bonds exist as a Giant Covalent Lattice.

  -As the ions are not free to move (they're are no delocalised electrons) they cannot conduct electricity.
• Explain why graphite can conduct electricity.

  -Graphite has delocalised electrons which act as charge carriers.
• Explain why diamonds are hard.

  -When solid, covalent bonds exist as a Giant Covalent Lattice

  -There are strong covalent bonds within the lattice and lots of bonds.

  -A lot of energy therefore is required to break these bonds.
• Explain why graphite is soft and slippery.

  -Graphite exists as layers of carbon atoms held together by weak forces of attraction.

  -It does not take much energy for the layers to slide over each other.
• What element are fullerenes and graphene made from ?

  Carbon.
• What is a graphene made of? Why are they useful?

  -Graphene is a single layer of graphite

  -It has properties that make it useful in electronics and composites.
• Describe the structure of graphene?

  Interlocking hexagonal rings of carbon.
• What are some properties of graphene?

  -excellent conductor of electrical and thermal energy

  -low density

  -most reactive form of carbon
• What is an example of a use of graphene?

  Graphene can be used for flexible electronic display, ie: watching a film on your coat sleeve.
• What is a fullerene?

  Hollow, cage-like carbon molecule
• What was the first fullerene to be discovered?

  The first fullerene to be discovered was Buckminsterfullerene (C60) which has a spherical shape.
• What are some properties of carbon nanotubes?

  -high tactile strength

  -high electrical and thermal conductors
• What can fullerenes be used for?

  -nanotechnology

  -electronics

  -materials.
• What are some example of alloys?

  Bronze and steel
• What is an alloy?

  A mixture of at least two element, one of which is a metal.
• Why are alloys harder than pure metals?

  -Alloys have different sized particles which disrupt regular layers of positive metal ions.

  -These layer cannot slide over each other as easily.

  -This makes alloys harder than pure metals.
• What are coarse particles often referred to as?

  PM10 or dust.
• What are the diameters for coarse particles?

  between 1 x 10-5 m and 2.5 x 10-6 m.
• What is the relationship between the side of cubes and SA:V ratio?

  As the side of cube decreases by a factor of 10 the surface area to volume ratio increases by a factor of 10.
• Are nano particles bigger than fine particles?

  No.